A communication terminal which performs communication using a non-contact communication method is known. Japanese Patent Laid-Open No. 2005-323264 describes a technique of detecting the remaining power of a power supply unit on a storage (tag) side in an RFID system, if the remaining power is low, alerting the reader, and causing it to display an alert about the remaining power in the tag. In this case, for example, an induced electromotive force enables power level detection and result notification without consuming power in the tag.
The technique described in Japanese Patent Laid-Open No. 2005-323264 cannot, for example, newly activate an application, although it can detect the remaining power on the tag side. Additionally, for example, even when the remaining power on the tag side is determined to be sufficient, activation of a new application may cause a power shortage. That is, the conventionally proposed technique has not considered a system which predicts power necessary for activation of an application to execute certain processing (e.g., data communication) and operates by receiving a corresponding amount of power.